HR: 1330h
AN: T42A-0271    [PDF]
TI: On Grain Boundary Wetting During Deformation
AU: * Majumder, S
EM: maju0003@umn.edu
AF: University of Minnesota, Department of Geology and Geophysics, 310 Pillsbury Drive SE, Minneapolis, MN 55455 United States
AU: Leo, P H
EM: phleo@aem.umn.edu
AF: University of Minnesota, Department of Aerospace Engineering and Mechanics, 110 Union St. SE, Minneapolis, MN 55455 United States
AU: Kohlstedt, D L
EM: dlkohl@umn.edu
AF: University of Minnesota, Department of Geology and Geophysics, 310 Pillsbury Drive SE, Minneapolis, MN 55455 United States
AB: We have developed a theoretical model of initiation of fluid segregation along grain boundaries in a solid fluid aggregate deforming under an applied shear stress. Prior to the application of stress, the fluid resides in triple grain junctions and partially wets all grain boundaries, but during deformation, the fluid may completely wet or dewet grain boundaries under tension or compression, respectively. The driving force for wetting or dewetting is provided by the normal stress at the tip of the fluid front along the grain boundary, solid-solid and solid-fluid interfacial energies and the fluid pressure at the tip of the fluid front. Kinetics of wetting or dewetting of grain boundaries under tension or compression, depends on the mobility parameter $\beta$, which is defined by the ratio of the rate of stress relaxation by grain boundary wetting to the rate of stress relaxation by grain boundary diffusion. The results from our numerical experiment indicate that, depending on the value of $\beta$, deformation can cause zero to complete wetting of the grain boundary under tensile normal stress. Based on the final wetting length along the grain boundary under tension and $\beta$, we divide the stress relaxation mechanism into the diffusive relaxation regime, the wetting regime, and the intermediate regime. In the wetting regime, most of the grain boundary fluid will segregate along the grain boundaries under tension and thus the geometry of the fluid distribution changes from a network of tubules along grain edges to a network of planar fluid films along those grain boundaries that are under tension during deformation.
DE: 3210 Modeling
DE: 3900 MINERAL PHYSICS
DE: 3947 Surfaces and interfaces
SC: Tectonophysics [T]
MN: 2003 Fall Meeting